1993 Buick Lesabre Repair Question
Mileage: 300,000 miles.
Code 18 cam/crank error
So, what causes code 18 and what should I do to correct it? Could the new cam sensor or crank sensor be the source? After completing the repairs I have driven the car about four weeks or so without any problems. I have even allowed the car to idle for fifteen minutes or so twice since the weather turned cold without any check engine lights coming on.
Asked by KimberlyWAnswer
Check the sensor's resistances and wiring back to the computer
Where can I find the wiring diagram for this; so I can traced the wires? There are a lot of wires coming in and out of the computer. Where can I get the info on checking the sensors?
Thanks for your answer.
No repair manual -you can download online with Mit1 or Alldata for a cheap price
I am purchasing the GM mechanical and electrical service manuals for my car. While I am waiting for them to arrive in the post I have this question. From reading on the net, a code 18 for this car is a mismatch between the cam and the crank sensor signals. This car has over 300,000 miles on the engine that I know of (third owner of the car). I am wondering if the timing could have slipped; if the timing chain could have slip since the chain is worn for sure and the tensioner could be weak. The car was running great until that morning I allowed it to warm.
Could be the timing chain has slipped and throwing it out of sequence
How can I check this for timing chain slipped? I have a scan tool on loan that can also capture the data stream. Would that tell me anything. I have checked the cam wiring and that appears to be OK, the ground terminal was making ground. Checking the crank wires will be harder and will do that tomorrow. I know the timing chain and gear needs to be replace in this engine but was hoping to wait until Spring to do that job.
I checked all the wiring and they check OK. I also did some voltage tests for the cam and fuel sensor at the PCM connector. Both were at 5 volts as per specs. I rotated the crank and the cam voltage would go from 5 volts to 0 volts, so the cam sensor is working. Could not check the crank sensor output but the car will crank. Could be there is a broken or bent vane on the 18X, but I don't see how that could happen sitting in the driveway warming up. I put everything back together and the car cranked but ran rough. Smoothed out some after it warmed a bit (could be the PCM recalibrating). Engine runs rough. No codes reported or stored but the engine is not idling correctly. Checked the coil packs and the secondary ohms reading on all coils was around 10K ohms (cheap meter); all gave the same reading. I connected a cornwell scan tool and captured the datastream. I can provide information from that if you can tell me what data you need to help me. I did see that the engine is running lean according to the scan tool. This is my only car so it needs to be running again. It ran great after the repairs mentioned above and just happened one morning while warming up.
Clean out the idle air control and EGR valve also check the actual fuel pressure
The EGR valve is clean, I did that when I had the previous trouble. Fuel pressure was checked during the previous problem and was within specs. The fuel filter has not been replaced in several years, so I could do that. Easy enough to do a new fuel pressure check. Will check the IAC.
When you do fuel pressure checks-you do it with and without the fuel filter same goes to the fuel pressure regulator w and w/o the regulator to be accurate atleast this is my way on troubleshooting the fuel system